As a measure for improving viewing angle dependence of gamma characteristics in liquid crystal display devices (for example, holding down excess brightness and the like in a screen), a liquid crystal display device has been proposed which controls a plurality of sub-pixels in a pixel to have different brightness, so as to display a halftone by an area coverage modulation of these sub-pixels (pixel division mode; for example, see Patent Literature 1).
As illustrated in FIG. 48, an active matrix substrate disclosed in Patent Literature 1 has a pixel region provided between two adjacent gate bus lines 112; a pixel electrode 121a is disposed on an upper end (part adjacent to the gate bus line) of the pixel region, a pixel electrode 121b is disposed midway of the pixel region; and a pixel electrode 121c is disposed on a lower end (adjacent to a following adjacent gate bus line) of the pixel region. The pixel electrode 121a and pixel electrode 121c are connected to a source draw-out wire 119 that is drawn out from a source electrode 116s of a transistor 116. The source draw-out wire 119 is connected to a control electrode 118; the control electrode 118 is overlapped by the pixel electrode 121b via an insulating layer. The middle pixel electrode 121b is capacitively coupled with the pixel electrodes 121a and 121c (capacitively coupled pixel division mode). In a liquid crystal display device that uses this active matrix substrate, sub-pixels corresponding to the pixel electrodes 121a and 121c serve as bright sub-pixels, and sub-pixels corresponding to the pixel electrode 121b serve as dark sub-pixels. Hence, a halftone is displayed by area coverage modulation of the bright sub-pixels (2 sub-pixels) and dark sub-pixel (1 sub-pixel).
It is known that, in such a liquid crystal display device of a capacitively coupled pixel division mode, image sticking occurs in the sub-pixel including the pixel electrode 121b due to an influence of an electric charge accumulated in the capacitively coupled pixel electrode 121b. 
Specifically, as shown in FIG. 49, a pixel electrode 61b which is directly connected to a source line 55 via a transistor 56 is electrically connected to the source line 55 every time the transistor 56 is turned ON per 1 frame. This allows an electric charge accumulated in the pixel electrode 61b during an OFF period of the transistor 56 to flow into the source line 55 during the ON period. Accordingly, there remains almost no direct current voltage component in the pixel electrode 61b, and therefore image sticking hardly occurs. Meanwhile, an electric charge accumulated in a pixel electrode 61a that is capacitively coupled with the pixel electrode 61b is preserved even if the transistor 56 is turned ON. Accordingly, there remains a direct current voltage component in the pixel electrode 61a. This causes image sticking in a sub-pixel including the pixel electrode 61a. As an example of a method for solving the image sticking problem, in the active matrix substrate disclosed in Patent Literature 1, the pixel electrode 121b that is capacitively coupled with the pixel electrode 121a is disposed to be away from the gate bus line 112 as shown in FIG. 48. That is, by disposing the pixel electrode 121b between the pixel electrode 121a and the pixel electrode 121c, it is possible to prevent a flow of an electric charge into the pixel electrode 121b caused by a direct current voltage component of a signal flowing through the gate bus line 112. In this way, it is possible to suppress occurrence of image sticking.
However, according to the arrangement, the pixel electrode 121b is still in a floating state. It is therefore impossible to completely prevent the inflow of the electric charge, thereby making it difficult to achieve high-quality display.
Non-Patent Literature 1 discloses an arrangement in which a pixel electrode that is in a floating state as described above is directly connected to a source line via a transistor. FIG. 50 is an equivalent circuit diagram illustrating part of a liquid crystal panel disclosed in Non-Patent Literature 1. As shown in FIG. 50, this liquid crystal panel has a pixel region (main pixel region (Main region) and a sub-pixel region (Sub region)) between two adjacent gate bus lines. A main pixel electrode corresponding to the main pixel region is connected to a source line (Data line) via a first transistor (Main-TFT), and a sub-pixel electrode corresponding to the sub-pixel region is connected to the source line via a second transistor (Sub-TFT). The first and second transistors are connected to an identical gate bus line (Gate line).
According to the arrangement, the source line and the sub-pixel electrode are electrically connected to each other when the first and second transistors are turned ON. This discharges (refreshes) an electric charge accumulated in the sub-pixel electrode. It is thus possible to suppress occurrence of image sticking of a sub-pixel including a pixel electrode that is in a floating state.